Non-Destructive Testing

ADVACAM’s X-ray digital radiography imaging detectors are an ideal solution for many Non-Destructive Testing (NDT) applications. The photon counting detectors provide improved sensitivity, spatial resolution, contrast and signal-to-noise ratio. The broad range of detectable X-ray energy starting from 5 keV up to hundreds of keV or even MeV let the detectors capture from very light composite materials up to thick welded parts. In addition, the energy discrimination helps suppress the scattered radiation and improving the contrast of measured images. NDT specialists and service providing companies can extend the portfolio of customers by those whose products could not be inspected by X-ray radiography in the past. Our new X-ray imaging technologies are useful for inspecting composite materials in the aerospace industry. Standard radiographic X-ray imaging provides a black and white intensity or density image of the inspected sample, where defects, impurities or cracks are observed if the resolution and the signal over the noise of the image is appropriate. The spectral NDT X-ray imaging based on photon counting provides additional material information of the samples together with a superior contrast and high spatial resolution. The spectral material information is used to discriminate different materials and identify the materials of interest. The spectral image taken with WidePIX 5x5 CdTe of a PCB unveils different components in different colors.

Non-destructive testing of welds and heavy objects

X-ray photon counting detectors are not only suitable for light materials. The highly sensitive CdTe sensors can also be used for welding inspection. The detectors, according to standard ISO 17636-2, achieve the Class B image quality. They are a perfect choice for cutting edge digital radiography NDT systems. The detectors can be either operated in frame mode or in time-delayed-integration mode, where they produce “endless” images as the detector moves along the object. The imaging quality of WidePIX 1x5 MPX3 imaging detector operated in the time-delayed-integration mode has been tested on BAM-5 and BAM-25 steel weld samples with IQI and DIQI attached.
The spatial resolution was measured using DIQI. The narrowest wire pair resolved was the D13 (50 μm wide wires with gap of 50 μm).
Detector contrast was evaluated using the 10FEEN IQI. All wires, including the wire 16 (0.1 mm thick), were resolved behind the 8.3 mm thick steel sample wall.
The signal-to-noise ratio measured (SNRm) achieved was of 148 in case of 8.3 mm thick BAM-5 sample. SNRm of 190 was measured for the BAM-25 which is of 6 mm thick steel. The SNRm was capped by the X-ray tube power. The detector has 24-bit counter depth therefore allowing SNRm as high as 4000.
The resulting SNRn (normalised on the detector resolution) was of 336 at 6 mm thick steel and 262 in the case of 8.3 mm thick steel.

Light materials and composites non-destructive testing solutions

ADVACAM brings to the market a new range of X-ray imaging cameras that are optimized for composite material testing. The sensitivity to low energies is useful for non-destructive testing of modern light materials. Combining the low X-ray energy detection, high sensitivity with the very high dynamic range of photon counting detectors creates a powerful tool for NDT in the aerospace industry and elsewhere.
Light materials, such as carbon fibres, epoxies, etc. are easily revealed in a great detail. Even challenging defects such as deep laminate wrinkles, porosity, foreign objects and micro-cracks in the soft materials can be detected with spatial resolution of 55 µm or better. The capabilities of photon counting detectors are further expanded by robotic systems developed by Radalytica a.s. Contrary to the classical X-ray imaging setups, the robotic system gives nearly absolute flexibility of viewing angles. Therefore, these robots allow X-raying from different perspectives, to better localise defects. The high frame rate of photon counting detectors also allows real-time inspection. Inspection is then for the NDT inspector as natural as if wearing “X-ray goggles”. Moreover, robots further open the possibility of using 3D imaging techniques, such as computed tomography or tomosynthesis. These are methods commonly used in X-ray imaging, but with limited applicability on large complicated shapes. Robots help overcome this limit. The robotic systems could be used in quality control labs or built into production lines.

Radalytica's robotic system prototype inspecting a glider aileron

Radalytica's robotic system prototype inspecting a glider aileron. The robot on left holds a compact X-ray tube. The X-ray imaging detector is mounted on the robotic arm on right. The final X-ray image reveals voids and impurities in the internal composite structure.

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